35.9 Thermal Specifications

Table 35-9. Thermal Specifications
Symbol Description Typ. Unit Conditions
θJA Thermal Resistance Junction to Ambient 60.0 °C/W 28-pin PDIP package (SP)
47.0 °C/W 28-pin SOIC package (SO)
67.1 °C/W 28-pin SSOP package (SS)
36.1 °C/W 32-pin VQFN package (RXB)
58.8 °C/W 32-pin TQFP package (PT)
33.7 °C/W 48-pin VQFN package (6LX)
55.6 °C/W 48-pin TQFP package (PT)
Note:
  1. Calculate power dissipation as follows:

    PDIS = VDD × {IDD - Σ IOH} + Σ {(VDD - VOH) × IOH} + Σ (VOI × IOL)

  2. Calculate Internal Power Dissipation as follows: PINTERNAL = IDD × VDD, where IDD is the current running the chip alone without driving any load on the output pins.
  3. Calculate Derated Power as follows: PDER = PDMAX (TJ-TA)/θJA, where TA = Ambient Temperature, TJ = Junction Temperature.